This invention relates generally to tools for mixing cementitious materials, and further to improved mixing blades for hand tools such as hoes and the like for mixing water or other fluids with dry cementitious materials to form slurries.
Cementitious materials such as concrete, mortar, tile grout, plaster and the like typically comes in bags as a “dry mix”. In order to be used, the dry mix material must be mixed with water or other fluids to form a slurry having an appropriate consistency. Generally, this is done by gradually adding water to the dry mix material and stirring or the water and the material using a hand tool such as a hoe, a trowel, or the like to completely and thoroughly mix the material and the water to form a uniform slurry of the desired consistency.
U.S. Pat. No. 5,947,039 to Lundgren et. al discloses a hand-held water injecting tool for gradually adding water to and mixing dry cementitious materials such as concrete. The Lundgren tool comprises a hoe-like device having a tubular handle for conveying water to a blade attached to a lower water outlet end of the handle, a connection for a conventional garden hose at the upper water inlet end of the handle, and a control valve to control the flow of water through the tubular handle to the blade. The lower end of the handle to which the blade is attached is flattened or crimped to form a pair of parallel ducts or channels that communicate with the interior of the handle to convey water from within the tubular handle to outlets at the ends of the ducts or channels to the surface of the blade. The control valve allows water to be added in a controlled manner to the dry material during mixing.
Lundgren discloses two different blade structures. The first is a solid planar triangularly-shaped blade having a lower end or tip with a rounded radius and having a top angled flange which extends outwardly from the plane of the blade to impart additional strength and stiffness to the blade. The triangularly-shaped blade is attached to the lower crimped end of the handle by fasteners, and is disclosed as facilitating slurryfying of cementitious dry mix materials by making penetration and movement through such materials less difficult. The second blade has an arrow-like or V-shaped design with a winged appearance with a pair of opposed left and right wing portions extending upwardly from a rounded radius tip, and has a tang bisecting the wing portions that extends into the lower crimped portion of the tubular handle for attachment thereto.
The triangularly-shaped blade of Lundgren operates in a similar way to a conventional hoe. The triangular shape of the blade allows the pointed end to penetrate the mixture more easily. However, the blade does not have the same area as a conventional hoe and it does not work well to mix thoroughly the dry cementitious materials, particularly concrete, and water to form the desired slurry. Also, the top angled flange of the blade allows materials to coagulate in lumps behind the flange and at the back of the blade. While the V-shaped blade performs somewhat better than the triangularly-shaped solid blade, it also does not perform satisfactorily in mixing concrete and other dry cementitious materials with water. Bagged concrete contains gravel, typically ⅜ inch pea gravel, which makes it more difficult than other types of cementitious materials to mix thoroughly into a uniform, consistent slurry. The angled sides of both blades allow the blades to scrape the sides of a wheelbarrow or other mixing container. However, their rounded tips do not allow the blades to scrape effectively the bottom of the mixing container.
There is a need for improved tools for mixing cementitious materials, including fluid injecting tools of the type disclosed in the Lundgren et. al patent, and it is to these ends that the present invention is directed.